Restoration and maintenance work is currently increasingly frequent, particularly in the historical centers of cities and towns, in the field of civil building and of municipal networks for supplying water, gas and power, both for protecting buildings and for servicing public utilities, such as gas pipelines, water pipelines and electrical grids.
This work requires very delicate excavation activities, since it is performed in ground which is already crossed by working pipes and cables, which therefore must absolutely be preserved against damage and failure.
Other work requiring similar precision and delicateness in operation is constituted for example by excavations in the vicinity of roots of plants or in regions crossed by rail tracks.
Other work requiring particular flexibility and precision in operation is work performed in underground spaces, which cannot be accessed by excavation vehicles.
In order to remove the soil, but also liquids or mud, from the ground to be excavated, apparatuses for removal by suction, particularly of soil, are currently known which comprise, supported by the chassis of a means of transport, a partial vacuum unit for a collection tank, to which the aspirated material is conveyed by associated suction means.
Said tank is installed on unloading means, which are suitable to lift it on one side in order to empty it by gravity of the material accumulated therein.
The soil or dust, liquids, mud and other similar material, aspirated and deposited in the tank, are emptied, when the tank is full, into a dump body, which is removable from a vehicle chassis and is generally arranged to the rear of the means of transport of the tank, since the actuators that lift the tank to empty it tilt it so as to unload from the rear of the means of transport.
This position for unloading operations requires occupying a very large area, in which the means of transport of the tank and the chassis-mountable dump body must be arranged in a line.
If these operations for removing soil by suction occur in urban areas, they are often carried out in relatively constrained spaces, for which passage and parking is difficult for large motor vehicles, such as typically excavators and earth removal machines in general, as well as for trucks for carrying the dump bodies.
These apparatuses for removing soil, mud and the like by suction are generally provided with a filtration device, which is constituted by a box-like body with a tapering bottom for collecting the filtrate and an upper lid.
Filtering shell-and-tube assemblies, covered at least partially with dust retention sleeves, or other filtering elements, depending on whether one has to filter soil, liquids or mud, are arranged within the box-like body.
The box-like body is conveniently cylindrical, i.e., has the shape that best withstands the stresses imposed by the partial vacuum generated inside it.
Said cylindrical shape of the body of the filtration device, however, causes considerable space occupation, especially in the longitudinal direction of the means of transport.
The width of such a filtration device in fact entails an equal length, since it is a cylindrical body, consequently reducing, on board the means of transport, the space available for the suction means and the collection tank.